Poached Pear Tart with Caramelized Pistachios

Finely grind pistachios and 3 tablespoons sugar in processor. Transfer nut mixture to heavy medium saucepan; add milk and bring to boil. Whisk remaining 4 tablespoons sugar, yolks, and cornstarch in medium bowl to blend. Gradually whisk hot milk mixture into yolk mixture. Return mixture to same pan; whisk constantly over medium-high heat until mixture boils and thickens, about 1 minute. Remove from heat. Whisk butter into pastry cream, 1 piece at a time. Transfer pastry cream to bowl; press plastic wrap directly onto surface. Cover and chill at least 4 hours. Stir in cream. (Can be made 2 days ahead. Keep chilled.)